This implementation expects a plain text string, which is prefixed and then signed by a wallet.
Because the spec calls for 1 message to be signed and 1 signer, this function expects a single
signature and used the first item in the sigPair array.
Parameters
message: string
A plain text string
base64SignatureMap: string
A base64 encoded proto.SignatureMap object
publicKey: default
Returns boolean
boolean - whether or not the first signature in the sigPair is valid for the message and public key
This implementation expects a plain text string, which is prefixed and then signed by a wallet. Because the spec calls for 1 message to be signed and 1 signer, this function expects a single signature and used the first item in the sigPair array.